returns to child investments, should also foster a reduction in the number of births parents want.
Prospects for Fertility
It may be premature to speculate on the timing and structure of fertility changes that will occur in the less developed world, but available data fall into a consistent pattern. Evidence of fertility levels by age, observed over time, for both high income countries and for the handful of low income countries in which birth rates have recently fallen sharply suggest that declines in fertility do not occur uniformly among women of all ages. Rather, birth rates for women in their 20's remain relatively high, and those for women over the age of 30 fall to relatively low levels after the period of demographic transition. In some countries there is also a concurrent drop in fertility among younger teen-age women, possibly related to delayed marriage, increased demand for adolescent schooling and diminished desired levels of fertility. In the posttransfusion environment parents appear to complete their families more quickly than was the case for earlier generations and to avert additional births rather successfully after the mother reaches the age of 30 or 35. If this pattern of reproductive behavior continues to spread in low income countries, we may anticipate the changes (mentioned earlier) in the allocation of family resources directly linked to the decline of fertility.
Employment of Women
A second aspect of the development process raises the cost of childbearing most notably. A significant part of child costs is the value of a mother's time spent attending to her children. When her most productive activities are easily combined with child rearing in the home, the opportunity cost of her time devoted to them is small and a large family no great inconvenience. However, the household activities traditionally performed by women, such as weaving, processing family food, caring for livestock, and handicraft cottage manufacturing tend to be displaced gradually in the development process by modern food processing and the textile and manufacturing sectors. They are also depreciated by the growing commercial specialization in agriculture. As development proceeds, the woman finds her most remunerative employment opportunities are increasingly outside of the home and even outside of the rural-agricultural sector of the economy (30). These employment opportunities are increasingly difficult to combine with child rearing. In this more specialized economic environment, a large family extracts from parents a growing opportunity cost for the mother's time that may force them to adopt a smaller family-size goal.
This mounting opportunity cost of child rearing reinforces the tendency
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